This paper presents a vision-based navigation framework for micro air vehicles(MAVs)operating in confined warehouse environments.To address the trade-off between low localization accuracy in mapless methods and high c...This paper presents a vision-based navigation framework for micro air vehicles(MAVs)operating in confined warehouse environments.To address the trade-off between low localization accuracy in mapless methods and high computational demands in map-based approaches,the proposed system leverages topology-aware path guidance using monocular vision.Navigation is driven by a digital instruction format(DIF)that encodes both the path index and target junction,enabling autonomous navigation without environmental modifications.The framework comprises a cascaded perception-encoding-control pipeline.For structured paths,foreground pixel density trend analysis with sliding window smoothing for robust junction recognition,while lateral proportionalintegral-derivative(PID)control ensures accurate path tracking.For geometric trajectories,the control logic incorporates L-junction triggers,fixed-angle turns,and spatial yaw correction to accommodate sharp corners and curved segments.ROS-Gazebo simulations validate the method’s effectiveness,achieving up to 94.40%junction recognition accuracy(92.01%on average),trajectory tracking errors below 0.1 m,and terminal localization deviations under 0.2 m.These results validate the method’s accuracy,stability,and suitability for computationally constrained MAV platforms in warehouse automation.展开更多
With the continuous development of artificial intelligence and machine learning techniques,there have been effective methods supporting the work of dermatologist in the field of skin cancer detection.However,object si...With the continuous development of artificial intelligence and machine learning techniques,there have been effective methods supporting the work of dermatologist in the field of skin cancer detection.However,object significant challenges have been presented in accurately segmenting melanomas in dermoscopic images due to the objects that could interfere human observations,such as bubbles and scales.To address these challenges,we propose a dual U-Net network framework for skin melanoma segmentation.In our proposed architecture,we introduce several innovative components that aim to enhance the performance and capabilities of the traditional U-Net.First,we establish a novel framework that links two simplified U-Nets,enabling more comprehensive information exchange and feature integration throughout the network.Second,after cascading the second U-Net,we introduce a skip connection between the decoder and encoder networks,and incorporate a modified receptive field block(MRFB),which is designed to capture multi-scale spatial information.Third,to further enhance the feature representation capabilities,we add a multi-path convolution block attention module(MCBAM)to the first two layers of the first U-Net encoding,and integrate a new squeeze-and-excitation(SE)mechanism with residual connections in the second U-Net.To illustrate the performance of our proposed model,we conducted comprehensive experiments on widely recognized skin datasets.On the ISIC-2017 dataset,the IoU value of our proposed model increased from 0.6406 to 0.6819 and the Dice coefficient increased from 0.7625 to 0.8023.On the ISIC-2018 dataset,the IoU value of proposed model also improved from 0.7138 to 0.7709,while the Dice coefficient increased from 0.8285 to 0.8665.Furthermore,the generalization experiments conducted on the jaw cyst dataset from Quzhou People’s Hospital further verified the outstanding segmentation performance of the proposed model.These findings collectively affirm the potential of our approach as a valuable tool in supporting clinical decision-making in the field of skin cancer detection,as well as advancing research in medical image analysis.展开更多
The performance of multi-user code to direct spreading bi-phase shift keying （DS-BPSK） direct impulse ultra wideband （UWB） systems under indoor multi-user and multi-path environment is analyzed and simulated. The ...The performance of multi-user code to direct spreading bi-phase shift keying （DS-BPSK） direct impulse ultra wideband （UWB） systems under indoor multi-user and multi-path environment is analyzed and simulated. The system output signals with Rake receiver are derived, then a simple and practical code selection scheme is given; i. e., with a large occupation to empty ratio of the repeating pulses, directly choosing those random or pseudo-random user codes with enough length and good co-relative orthogonal features will make the performance of DS-BPSK approximate the optimum and, so there is no need to carefully design the code or its type. The system multi-access performances are simulated using Gold sequence and PN codes as multi-user codes under CMI-CM4 multi-path channels. Simulation results prove that the proposed scheme is feasible.展开更多
Five samples of LiMgPO_(4):Gd were prepared via five different production processes using a solid-state reaction method.The effects of the preparation process on optically stimulated luminescence(OSL)and thermolumines...Five samples of LiMgPO_(4):Gd were prepared via five different production processes using a solid-state reaction method.The effects of the preparation process on optically stimulated luminescence(OSL)and thermoluminescence(TL)were investigated.Considering its high sensitivity,low fading,and minimum detectable dose(MDD),the LiMgPO_(4):Gd phosphor heated to 900℃for 15 h is concluded to be optimal.The effects of annealing on the OSL sensitivity,relative residual OSL signals measured after 24 h of irradiation,and MDD of LiMgPO_(4):Gd phosphors heated to 900℃for 15 h were also investigated.Considering its high sensitivity,low fading,and MDD,annealing at 350℃for 1 h is concluded to be optimal.The OSL signal of LiMgPO_(4):Gd was derived from the principal TL glow peak.For a maximum integration time of 5 s,the OSL signal was stable,with no fading 30 days after irradiation.LiMgPO_(4):Gd eliminated approximately 2.2%of the OSL signal at each readout for a readout time of 0.1 s,which is sufficient for fast and multiple OSL readout.The sensitivity of LiMgPO_(4):Gd phosphor,annealed for 1 h at 350℃with a reading time of 0.1 s,was found to be approximately 98%of that observed forα-Al_(2)O_(3):C(TLD-500k),which should be sufficient for low-dose measurements in personal,workplace,and environmental dosimetry.展开更多
文中研究了中继合作协议下具有多面体不确定性系统的鲁棒模型预测控制问题。为了缓解网络化控制系统中远距离传输中的信道严重衰落问题,将放大转发中继合作协议应用到传感器和远程控制器通信链路中,从而提高信号传输质量。由于难以获取...文中研究了中继合作协议下具有多面体不确定性系统的鲁棒模型预测控制问题。为了缓解网络化控制系统中远距离传输中的信道严重衰落问题,将放大转发中继合作协议应用到传感器和远程控制器通信链路中,从而提高信号传输质量。由于难以获取实际系统状态,文中提出了RMPC(Robust Model Predictive Control)框架下的动态输出反馈控制策略。由于传感器和放大转发中继传输功率存在随机性,引入一组具有特定概率分布的随机变量来表征其发射功率。利用奇异值分解技术处理由未知变量耦合引起的非凸问题,提出辅助可解优化问题并得到底层系统的均方稳定性的充分条件。实验结果表明,所提控制框架使系统的控制性能更好,验证了该控制策略的有效性。展开更多
A multi-path routing algorithm based on network coding is proposed for combating long propagation delay and high bit error rate of space information networks.On the basis of traditional multi-path routing,the algorith...A multi-path routing algorithm based on network coding is proposed for combating long propagation delay and high bit error rate of space information networks.On the basis of traditional multi-path routing,the algorithm uses a random linear network coding strategy to code data pack-ets.Code number is determined by the next hop link status and the number of current received packets sent by the upstream node together.The algorithm improves retransmission and cache mechanisms through using redundancy caused by network coding.Meanwhile,the algorithm also adopts the flow distribution strategy based on time delay to balance network load.Simulation results show that the proposed routing algorithm can effectively improve packet delivery rate,reduce packet delay,and enhance network performance.展开更多
Wireless sensor networks are widely used for its flexibility, but they also suffer from problems like limited capacity, large node number and vulnerability to security threats. In this paper, we propose a multi-path r...Wireless sensor networks are widely used for its flexibility, but they also suffer from problems like limited capacity, large node number and vulnerability to security threats. In this paper, we propose a multi-path routing protocol based on the credible cluster heads. The protocol chooses nodes with more energy remained as cluster heads at the cluster head choosing phase, and then authenticates them by the neighbor cluster heads. Using trust mechanisms it creates the credit value, and based on the credit value the multi-path cluster head routing can finally be found. The credit value is created and exchanged among the cluster heads only. Theoretical analysis combined with simulation results demonstrate that this protocol can save the resource, prolong the lifetime, and ensure the security and performance of the network.展开更多
An algorithm of traffic distribution called active multi-path routing(AMR)in active network is proposed.AMR adopts multi-path routing and applies nonlinear optimizeapproximate method to distribute network traffic amon...An algorithm of traffic distribution called active multi-path routing(AMR)in active network is proposed.AMR adopts multi-path routing and applies nonlinear optimizeapproximate method to distribute network traffic among multiple paths.It is combined to bandwidthresource allocation and the congestion restraint mechanism to avoid congestion happening and worsen.So network performance can be improved greatly.The frame of AMR includes adaptive trafficallocation model,the conception of supply bandwidth and its'allocation model,the principle ofcongestion restraint and its'model,and the implement of AMR based on multi-agents system in activenetwork.Through simulations,AMR has distinct effects on network performance.The results show AMRisa valid traffic regulation algorithm.展开更多
Large-scale and diverse businesses based on the cloud computing platform bring the heavy network traffic to cloud data centers.However,the unbalanced workload of cloud data center network easily leads to the network c...Large-scale and diverse businesses based on the cloud computing platform bring the heavy network traffic to cloud data centers.However,the unbalanced workload of cloud data center network easily leads to the network congestion,the low resource utilization rate,the long delay,the low reliability,and the low throughput.In order to improve the utilization efficiency and the quality of services(QoS)of cloud system,especially to solve the problem of network congestion,we propose MTSS,a multi-path traffic scheduling mechanism based on software defined networking(SDN).MTSS utilizes the data flow scheduling flexibility of SDN and the multi-path feature of the fat-tree structure to improve the traffic balance of the cloud data center network.A heuristic traffic balancing algorithm is presented for MTSS,which periodically monitors the network link and dynamically adjusts the traffic on the heavy link to achieve programmable data forwarding and load balancing.The experimental results show that MTSS outperforms equal-cost multi-path protocol(ECMP),by effectively reducing the packet loss rate and delay.In addition,MTSS improves the utilization efficiency,the reliability and the throughput rate of the cloud data center network.展开更多
基金supported by the Fundamental Research Grant Scheme(FRGS)(No.FRGS/1/2024/TK04/USM/02/3)funded by the Malaysian Ministry of Higher Education(MOHE).
文摘This paper presents a vision-based navigation framework for micro air vehicles(MAVs)operating in confined warehouse environments.To address the trade-off between low localization accuracy in mapless methods and high computational demands in map-based approaches,the proposed system leverages topology-aware path guidance using monocular vision.Navigation is driven by a digital instruction format(DIF)that encodes both the path index and target junction,enabling autonomous navigation without environmental modifications.The framework comprises a cascaded perception-encoding-control pipeline.For structured paths,foreground pixel density trend analysis with sliding window smoothing for robust junction recognition,while lateral proportionalintegral-derivative(PID)control ensures accurate path tracking.For geometric trajectories,the control logic incorporates L-junction triggers,fixed-angle turns,and spatial yaw correction to accommodate sharp corners and curved segments.ROS-Gazebo simulations validate the method’s effectiveness,achieving up to 94.40%junction recognition accuracy(92.01%on average),trajectory tracking errors below 0.1 m,and terminal localization deviations under 0.2 m.These results validate the method’s accuracy,stability,and suitability for computationally constrained MAV platforms in warehouse automation.
基金funded by Zhejiang Basic Public Welfare Research Project,grant number LZY24E060001supported by Guangzhou Development Zone Science and Technology(2021GH10,2020GH10,2023GH02)+1 种基金the University of Macao(MYRG2022-00271-FST)the Science and Technology Development Fund(FDCT)of Macao(0032/2022/A).
文摘With the continuous development of artificial intelligence and machine learning techniques,there have been effective methods supporting the work of dermatologist in the field of skin cancer detection.However,object significant challenges have been presented in accurately segmenting melanomas in dermoscopic images due to the objects that could interfere human observations,such as bubbles and scales.To address these challenges,we propose a dual U-Net network framework for skin melanoma segmentation.In our proposed architecture,we introduce several innovative components that aim to enhance the performance and capabilities of the traditional U-Net.First,we establish a novel framework that links two simplified U-Nets,enabling more comprehensive information exchange and feature integration throughout the network.Second,after cascading the second U-Net,we introduce a skip connection between the decoder and encoder networks,and incorporate a modified receptive field block(MRFB),which is designed to capture multi-scale spatial information.Third,to further enhance the feature representation capabilities,we add a multi-path convolution block attention module(MCBAM)to the first two layers of the first U-Net encoding,and integrate a new squeeze-and-excitation(SE)mechanism with residual connections in the second U-Net.To illustrate the performance of our proposed model,we conducted comprehensive experiments on widely recognized skin datasets.On the ISIC-2017 dataset,the IoU value of our proposed model increased from 0.6406 to 0.6819 and the Dice coefficient increased from 0.7625 to 0.8023.On the ISIC-2018 dataset,the IoU value of proposed model also improved from 0.7138 to 0.7709,while the Dice coefficient increased from 0.8285 to 0.8665.Furthermore,the generalization experiments conducted on the jaw cyst dataset from Quzhou People’s Hospital further verified the outstanding segmentation performance of the proposed model.These findings collectively affirm the potential of our approach as a valuable tool in supporting clinical decision-making in the field of skin cancer detection,as well as advancing research in medical image analysis.
文摘The performance of multi-user code to direct spreading bi-phase shift keying （DS-BPSK） direct impulse ultra wideband （UWB） systems under indoor multi-user and multi-path environment is analyzed and simulated. The system output signals with Rake receiver are derived, then a simple and practical code selection scheme is given; i. e., with a large occupation to empty ratio of the repeating pulses, directly choosing those random or pseudo-random user codes with enough length and good co-relative orthogonal features will make the performance of DS-BPSK approximate the optimum and, so there is no need to carefully design the code or its type. The system multi-access performances are simulated using Gold sequence and PN codes as multi-user codes under CMI-CM4 multi-path channels. Simulation results prove that the proposed scheme is feasible.
文摘Five samples of LiMgPO_(4):Gd were prepared via five different production processes using a solid-state reaction method.The effects of the preparation process on optically stimulated luminescence(OSL)and thermoluminescence(TL)were investigated.Considering its high sensitivity,low fading,and minimum detectable dose(MDD),the LiMgPO_(4):Gd phosphor heated to 900℃for 15 h is concluded to be optimal.The effects of annealing on the OSL sensitivity,relative residual OSL signals measured after 24 h of irradiation,and MDD of LiMgPO_(4):Gd phosphors heated to 900℃for 15 h were also investigated.Considering its high sensitivity,low fading,and MDD,annealing at 350℃for 1 h is concluded to be optimal.The OSL signal of LiMgPO_(4):Gd was derived from the principal TL glow peak.For a maximum integration time of 5 s,the OSL signal was stable,with no fading 30 days after irradiation.LiMgPO_(4):Gd eliminated approximately 2.2%of the OSL signal at each readout for a readout time of 0.1 s,which is sufficient for fast and multiple OSL readout.The sensitivity of LiMgPO_(4):Gd phosphor,annealed for 1 h at 350℃with a reading time of 0.1 s,was found to be approximately 98%of that observed forα-Al_(2)O_(3):C(TLD-500k),which should be sufficient for low-dose measurements in personal,workplace,and environmental dosimetry.
文摘文中研究了中继合作协议下具有多面体不确定性系统的鲁棒模型预测控制问题。为了缓解网络化控制系统中远距离传输中的信道严重衰落问题,将放大转发中继合作协议应用到传感器和远程控制器通信链路中,从而提高信号传输质量。由于难以获取实际系统状态,文中提出了RMPC(Robust Model Predictive Control)框架下的动态输出反馈控制策略。由于传感器和放大转发中继传输功率存在随机性,引入一组具有特定概率分布的随机变量来表征其发射功率。利用奇异值分解技术处理由未知变量耦合引起的非凸问题,提出辅助可解优化问题并得到底层系统的均方稳定性的充分条件。实验结果表明,所提控制框架使系统的控制性能更好,验证了该控制策略的有效性。
基金supported by the National Natural Science Foundation of China(No.60929003)
文摘A multi-path routing algorithm based on network coding is proposed for combating long propagation delay and high bit error rate of space information networks.On the basis of traditional multi-path routing,the algorithm uses a random linear network coding strategy to code data pack-ets.Code number is determined by the next hop link status and the number of current received packets sent by the upstream node together.The algorithm improves retransmission and cache mechanisms through using redundancy caused by network coding.Meanwhile,the algorithm also adopts the flow distribution strategy based on time delay to balance network load.Simulation results show that the proposed routing algorithm can effectively improve packet delivery rate,reduce packet delay,and enhance network performance.
文摘Wireless sensor networks are widely used for its flexibility, but they also suffer from problems like limited capacity, large node number and vulnerability to security threats. In this paper, we propose a multi-path routing protocol based on the credible cluster heads. The protocol chooses nodes with more energy remained as cluster heads at the cluster head choosing phase, and then authenticates them by the neighbor cluster heads. Using trust mechanisms it creates the credit value, and based on the credit value the multi-path cluster head routing can finally be found. The credit value is created and exchanged among the cluster heads only. Theoretical analysis combined with simulation results demonstrate that this protocol can save the resource, prolong the lifetime, and ensure the security and performance of the network.
基金Supported by the National Natural Science Foun dation of China(90204008)
文摘An algorithm of traffic distribution called active multi-path routing(AMR)in active network is proposed.AMR adopts multi-path routing and applies nonlinear optimizeapproximate method to distribute network traffic among multiple paths.It is combined to bandwidthresource allocation and the congestion restraint mechanism to avoid congestion happening and worsen.So network performance can be improved greatly.The frame of AMR includes adaptive trafficallocation model,the conception of supply bandwidth and its'allocation model,the principle ofcongestion restraint and its'model,and the implement of AMR based on multi-agents system in activenetwork.Through simulations,AMR has distinct effects on network performance.The results show AMRisa valid traffic regulation algorithm.
基金supported by the National Key Research and Development Program of China(2018YFB1003702)the National Natural Science Foundation of China(61472192)the Scientific and Technological Support Project(Society)of Jiangsu Province(BE2016776)
文摘Large-scale and diverse businesses based on the cloud computing platform bring the heavy network traffic to cloud data centers.However,the unbalanced workload of cloud data center network easily leads to the network congestion,the low resource utilization rate,the long delay,the low reliability,and the low throughput.In order to improve the utilization efficiency and the quality of services(QoS)of cloud system,especially to solve the problem of network congestion,we propose MTSS,a multi-path traffic scheduling mechanism based on software defined networking(SDN).MTSS utilizes the data flow scheduling flexibility of SDN and the multi-path feature of the fat-tree structure to improve the traffic balance of the cloud data center network.A heuristic traffic balancing algorithm is presented for MTSS,which periodically monitors the network link and dynamically adjusts the traffic on the heavy link to achieve programmable data forwarding and load balancing.The experimental results show that MTSS outperforms equal-cost multi-path protocol(ECMP),by effectively reducing the packet loss rate and delay.In addition,MTSS improves the utilization efficiency,the reliability and the throughput rate of the cloud data center network.
